I said the same thing a couple of months ago when all the rumors about the new mini were kicking about. Would be pretty awesome for server farms too. You could fit 4x ATV size units in the same rack-space as one current mini.I wouldn't be surprised to see a Mac mini with the footprint of the Apple TV. There is a lot of wasted space in the current M1 Mini.
The mini really hasn't changed in 12 years now so it'd be nice to see a balls-out facelift, but somehow I think they'll stick to the older design so they can forgo external PSU's